<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <script>
    let a = Symbol()
  let b = Symbol()
  console.log(a===b);
  var obj={
    name: 'name',
    [a]:'Symbol'
  }
  //对象 key支持 字符串 和Symbol
//但是 Symbol 是不可列举的
for(let key in obj){
  console.log(key);
}
console.log(object.get)
function getArea(shapName){
  switch(shapName){
    case 'sanjiao': return .5*10*5;
    case 'chang': return 10*5;
   } //魔法字符串
}
getArea('sanjiao');
getArea('chang');
  </script>

</body>
</html>